152 CRUSTACEANS. 



by those in their ultimate and most perfect form that this is evidenced, 

 for it appears in an early stage, and long preceding the ultimate state. 

 The common cabbage caterpillar secures itself by a cord for preservation 

 during the season of inactivity, there to await its proximate change to 

 the chrysaUs, and one more remote, to the butterfly. The bee stores its 

 cells with provision of one kind for itself, and another for its young ; 

 the spider spins the web, wherein its prey is captured ; and the ant con- 

 structs subterranean galleries to favour its predatory habits. 



Nothing to be compared to any such artifices, is found among any 

 of the Crustaceans that I have seen. 



Like so many insects, they ai'e distinguished by segmentine di\dsions 

 of the body, whereof Dr Milne Edwards, in his comprehensive work, 

 enumerates twenty-one, — that is, indications equivalent to twenty-one. 



Practically viewed by the less learned, the principal divisions are 

 not rated at more than two in the crab, that is the main shell, back, or 

 carapace, and the thorax bearing the Umbs, attached to it, which two 

 may be rent asunder, the latter separating entire. 



As I do not purpose entering on the anatomical details of the struc- 

 ture of these animals, for which other naturalists are infinitely better 

 qualified, as shewn in the work just referred to, I shall confine mj'self 

 to different topics chiefly receiving very httle notice, comparatively. 



The ordinary external colour of the Cancer mcenas is green, which 

 is sometimes variegated by an intermixture of white, seldom permanent 

 throughout life, the latter being gradually obliterated ; and some are 

 entirel};- reddish, especially with advancing age. 



The specimen, Plate XXXIV. fig. 1, was green and white, the former 

 greatly predominating. The specimen, Plate XXXV. fig. 1, was almost 

 white, with red eyes ; and the specimen, fig. 2, of the same Plate, had 

 the back red, patches on the claws and limbs, and the rest white. 



The specimen, Plate XXXIII. figs. 1, 2, preserved its proper colour 

 very long ; but at length the white was obscured, and a tendency of 

 the whole to red ensued. 



Certain interesting facts relative to the derivation of colour, in 

 either plain or variegated crabs, are of difficult explanation. 



